Could be more of a local deal, but I was in the Best Buy Outlet in San Rafael, CA today, and they had about a dozen Sonos Subs listed for $476 each. Some were in Sonos boxes, others were in plain cardboard boxes. All were black.
There was one last white one left that was marked at $455, but when I checked out it rung up for $420, so the black ones may ring up lower. $476 is still a pretty good price. My white one looks brand new, I think they all just have damaged packaging but are unused.
In any case, maybe the other outlets have them. Link to the outlet locations.